Known gas turbine engines generally include rows of circumferentially spaced nozzles and buckets. A turbine bucket generally includes an airfoil having a pressure side and a suction side and extending radially upward from a platform. A hollow shank portion may extend radially downward from the platform and may include a dovetail and the like so as to secure the turbine bucket to a turbine wheel. The platform generally defines an inner boundary for the hot combustion gases flowing through a gas path. As such, the platform may be an area of high stress concentrations due to the hot combustion gases and the mechanical loading thereon. In order to relieve a portion of the thermally induced stresses, a turbine bucket may include some type of platform cooling scheme or other arrangements so as to reduce the temperature differential between the top and the bottom of the platform.
Various types of platform cooling arrangements are known. For example, a number of film cooling holes may be defined in the turbine bucket between the shank portion and the platform. Cooling air may be introduced into a hollow cavity of the shank portion and then may be directed through the film cooling holes to cool the platform in the localized region of the holes. Another known cooling arrangement includes the use of a cored platform. The platform may define a cavity through which a cooling medium may be supplied. These known cooling arrangements, however, may be difficult and expensive to manufacture and may require the use of an excessive amount of air or other type of cooling medium.
There is therefore a desire for an improved turbine bucket for use with a gas turbine engine. Preferably such a turbine bucket may provide cooling to the platform and other components thereof without excessive manufacturing and operating costs and without excessive cooling medium losses for efficient operation and an extended component lifetime.